Quasi‐Localized High‐Concentration Electrolytes for High‐Voltage Lithium Metal Batteries

Abstract

The poor compatibility with Li metal and electrolyte oxidation stability preclude the utilization of commercial ester‐based electrolytes for high‐voltage lithium metal batteries. This work proposes a quasi‐localized high‐concentration electrolyte (q‐LHCE) by partially replacing solvents in conventional LiPF6 based carbonated electrolyte with fluorinated analogs (fluoroethylene carbonate (FEC), 2,2,2‐trifluoroethyl methyl carbonate (FEMC)) with weakly‐solvating ability. The q‐LHCE enables the formation of an anion‐rich solvation sheath, which functions like LHCE but differs in the partial participation of weakly‐solvating cosolvent in the solvation structure. With this optimized electrolyte, inorganic‐dominated solid electrolyte interphases are achieved on both the cathode and anode, leading to uniform Li deposition, suppressed electrolyte decomposition and cathode deterioration. Consequently, q‐LHCE supports stable cycling of Li | LiCoO2 (≈3.5 mAh cm−2) cells at 4.5 V under the whole climate range (from −20 to 45 °C) with limited Li consumption. A practical ampere‐hour level graphite | LiCoO2 pouch cell at 4.5 V and aggressive Li | LiNi0.5Mn1.5O4 cell at 5.0 V with excellent capacity retention further reveals the effectiveness of q‐LHCE. The refinement of old‐fashioned carbonate electrolytes provides new perspectives toward practical high‐voltage battery systems.

Tuning the End Alkyl Chain of the Ether Solvent to Stabilize the Electrode/Electrolyte Interfaces in the NCM-Li Battery

“…This discovery affirms that within the long-chain ether system, the CEI film component on the surface of the weakly solvated electrolyte contains more LiF when contrasted with the local highconcentration electrolyte. 39 The reaction products of WSE contribute to the formation of CEI rich in inorganic substances, thereby achieving more efficient and uniform lithium ion transport.…”

“…As inferred from the figure, compared with the local high-concentration electrolyte, the electrode surface after 50 cycles in the weakly solvated electrolyte displays a higher content of LiF components. This discovery affirms that within the long-chain ether system, the CEI film component on the surface of the weakly solvated electrolyte contains more LiF when contrasted with the local high-concentration electrolyte . The reaction products of WSE contribute to the formation of CEI rich in inorganic substances, thereby achieving more efficient and uniform lithium ion transport.…”

N-Rich Bilayer Solid Electrolyte Interphase toward Highly Reversible Lithium Metal Batteries

“…According to previous studies, electrolytes can modulate Li nuclei morphology and interfacial reaction by modulating solid electrolyte interphase (SEI) chemistry, nanostructure, and ion transport properties. Thus, electrolyte optimization, including concentrated electrolytes, localized high-concentration electrolytes, , fluorinated solvents, and electrolyte additives, as efficient interface modification strategies, is considered to extend lifespan. Notably, polymer–inorganic interlayers are recommended to be constructed by the prioritized decomposition of organic additives (e.g., fluoroethylene carbonate), , while not facilitating long-term cycling.…”

“…It is a pity that the artificial layer might be damaged during the repeated plating/ striping due to serious volume change. 17 lytes, 18 localized high-concentration electrolytes, 19,20 fluorinated solvents, 21 and electrolyte additives, 22 as efficient interface modification strategies, is considered to extend lifespan. Notably, polymer−inorganic interlayers are recommended to be constructed by the prioritized decomposition of organic additives (e.g., fluoroethylene carbonate), 23,24 while not facilitating long-term cycling.…”

Engineering High-Performance Li Metal Batteries through Dual-Gradient Porous Cu-CuZn Host

“…Lithium (Li) metal anodes (LMAs) represent a promising energy storage technology based on electrochemical conversion reactions, offering a theoretical specific capacity of up to 3860 mAh g –1 , surpassing conventional Li-ion intercalation chemistry. − This surpasses the gravimetric capacity offered by conventional Li-ion intercalation chemistry, playing a pivotal role in advancing high-energy-density battery systems. − However, the progress of LMAs faces two primary challenges: the nonuniform nucleation and deposition behavior of Li metal, as well as the subsequent growth of Li dendrites resulting from these processes. − Researchers have extensively explored strategies to stabilize LMAs, encompassing anode structure design, − anode interface engineering, − separator engineering, − and electrolyte modification. − Through these efforts, the growth model of Li dendrites has been essentially elucidated. The suppression of Li dendrites and the development of techniques for inducing uniform nucleation/deposition of metallic Li have made significant advancements and garnered widespread consensus. − …”